1. Field of the Invention
This invention relates to a method of generation of charged particle beam exposure data and a charged particle beam exposure method using a block mask, and in particular relates to an exposure data generation method and exposure method enabling the partial use of a block mask.
2. Description of the Related Art
In charged particle beam exposure methods, an electron beam or other charged particle beam is formed into a desired pattern and made incident on a resist layer on a wafer or mask which is the object for exposure, to form a fine pattern. In order to accommodate demands in recent years for finer patterns, wafers are directly irradiated with electron beams.
In a charged particle beam exposure method (below, an electron beam exposure method is considered as one such example), an electron beam formed by an electron gun is caused to pass through a first slit having a rectangular transmission aperture, to form a rectangular first transmission beam; this first transmission beam is further made partially incident on a second slit having a rectangular transmission aperture, to generate a second transmission beam formed into the desired rectangular shape, which is made incident on the wafer. Because of the increased number of patterns for exposure accompanying higher LSI integration levels, exposure using the above-described variable rectangular beam results in lowered throughput.
Hence it has been proposed that in the case of repeating patterns, a mask having the pattern of the unit of repetition is formed, and in place of a second slit, the first transmission beam be made incident on this repeating-pattern mask, causing an electron beam formed into the repeating pattern to be incident on the wafer. This is for example described in Japanese Patent Laid-open No. H04-100208. This method is called the partial batch transfer exposure method, because a portion of a plurality of LSI patterns is exposed all at once. Because the repeating pattern mask corresponds to a partial block mask, this method is also called a block exposure method. In this specification, “block exposure method” is used.